1. Technical Field
The present disclosure relates to a cogenerating system.
2. Description of the Related Art
A Rankine cycle apparatus is available as a power generating apparatus. Another available system in the related art includes a Rankine cycle, and a heat transfer circuit including a condenser that operates as an evaporator of the Rankine cycle and is connected to the Rankine cycle.
U.S. Pat. No. 8,141,362 discloses a system 300 including a heat transfer circuit 340 and a Ranking cycle 350 as illustrated in FIG. 9. The heat transfer circuit 340 includes a boiler 310 as an evaporator, a condenser 313, a first fluid duct 312, a second fluid duct 315, an expander 316, an additional condenser 323, and a valve 324. The first fluid duct 312 connects the outlet of the boiler 310 to the condenser 313. The second fluid duct 315 is connected to the condenser 313 to return a condensed fluid to the boiler 310. The heat transfer circuit 340 is filled with water. The additional condenser 323 is selectively connected to the second fluid duct 315 by the valve 324. The Ranking cycle 350 includes the condenser 313, an expander 330, an economizer 331, a condenser 332, a pump 333, and a heating circuit 334a. The condenser 313 functions as an evaporator in the Ranking cycle 350.
The boiler 310, if operated, generates vapor, and part of the boiler 310 and the first fluid duct 312 are filled with vapor. When vapor reaches the condenser 313, the condenser 313 performs a heat exchange operation. Heat is thus conducted from the boiler 310 to the condenser 313 via the first fluid duct 312. As an amount of heat continues to increase, vapor spreads, increasing pressure and temperature thereof. An amount of heat transfer increases in the condenser 313. If the pressure in the heat transfer circuit 340 exceeds a predetermined level, the valve 324 automatically opens for safety purposes, causing the additional condenser 323 to remove excessive heat. The pressure of vapor falls to an appropriate level.
As the vapor condenses in the condenser 313, a working fluid of the Ranking cycle 350 evaporates. Resulting vapor drives the expander 330, generating motive power before low-pressure vapor is condensed in the condenser 332. The working fluid is then returned to the condenser 313 by the pump 333. The condenser 332 radiates heat of the low-pressure vapor to the heating circuit 334a. 
The system 300 disclosed in U.S. Pat. No. 8,141,362 has room for improvements in terms of adaptability to a large amount of heat demand.